A large variety of fabrics and zippers for garments are available and used by the textile industry.
Fabrics for garments can be stretchable, elastic or rigid. Materials available for garment fabrics comprise plant textiles, animal textiles, synthetic textiles, artificial textiles and mineral textiles.
The manufacturing processes for producing garments comprise treatments of fabrics such that, depending on the typology of the fabric, when the fabric of the garment is washed, it may undergo to shrinkage. In particular, bi-stretch material fabrics present a considerable shrinkage, up to 20%, after washing. The term “bi-stretch material” used before and hereinafter refers to an elastic material fabric used especially for denim garment, that can be stretched along the warp and weft directions.
Zippers, zip fasteners or clasp locker, are common devices used for binding the edges of any separable portions that define an opening in a garment; a typical example of separable portions are fly pieces of fabrics in garments. A zipper comprises zipper teeth and a zipper tape. Different materials are available for zippers teeth and zippers tapes. Typically, zippers teeth materials include nylon coil, metal and plastic teeth, while zippers tapes materials include polyester, nylon and many other woven elastic and non-elastic materials.
When a zipper is fastened to the garment's separable portions and then the garment is washed, the zipper and the fabric to which the zipper is fastened, may undergo a different shrinkage. In particular, if the zipper tape material is, as commonly used, polyester, the zipper does not shrink or shrinks very little. On the contrary, if the fabric of the garment is a mono or bi-stretch material, it will undergo shrinkage after washing. In general, when the fabric of the garments and the zipper tape undergo washing, there occurs a different shrinkage of the fabric and the zipper that generates wavy-looking folds on the region of the garment where the zipper has been sewn. The term “wavy-looking folds” used before and hereinafter, refers to a corrugated region of the garment where the fabric and/or the zipper shrink forming a substantially oscillating profile. As a result, the undesired wavy-looking folds aesthetically ruin the design of the garment. Moreover, this may cause a malfunctioning of the zipper since the zipper has to slide through wavy-looking folds of the tape.
Since non-elastic zippers, such as 100% polyester zippers, do not shrink after washing, the application of such zipper to a fabric that does not shrink after washing, does not generates any problem. However, if the fabric of the garment undergoes shrinkage after washing, the application of a non-elastic or an elastic zipper will produce a corrugated region in the garment.
In fact, in the case of a zipper applied on stretchable garment separable portions, after washing the garment, the separable portions undergo shrinkage, while the non-elastic zip does not. Therefore, the shrinkage of the garment separable portions generates the wavy-looking folds described before.
The problem of garment shrinkage after washing, in particular referring to the wavy-looking folds on the region where the zipper is sewn, is also disclosed in CN2513408Y. The malfunctioning of the zipper caused by the wavy-looking folds on the garment can be solved by providing the zipper structure with a head body comprising a pull tab so that when the tab is pulled by the zipper, it provides a levelling effect that improves the zipper scroll when it is slid to a closed or open position.
However, even if this solves the problem of the zipper malfunctioning under the fabric shrinkage after washing, the fabric and the zipper tape still present undesired wavy-looking folds. This problem persists both in the open and closed condition of the zipper, causing an unpleasant wavy-look of the garment in correspondence of the zipper.